Hydraulically operated power press

ABSTRACT

A HYDRAULICALLY OPERATED POWER PRESS COMPRISES TWO HORIZONTALLY SPACED UPRIGHT MEMBER WHICH ARE INTERCONNECTED BY MEANS OF A TORSIONPROOF SHAFT MOUNTED BETWEEN THEM, AND AN UPPER TORSIONPROOF CROSS MEMBER WHICH EXTENDS PARALLEL TO SAID SHAFT. TWO LEVER TUMBLERS ARE MOUNTED ON SAID SHAFT AND EXTEND IN CLOSE PARALLEL RELATIONSHIP TO THE INNER SIDES OF SAID UPRIGHT MEMBERS. A PRESS BEAM IS ASSOCIATED WITH SAID TWO LEVER TUMBLERS THROUGH THE INTERMEDIARY OF TWO PRESSURE BARS PIVOTED TO   ONE END OF EACH OF SAID LEVER TUMBLERS. TWO HYDRAULIC RAMS ARE PROVIDED TO ACT UPON THE OPPOSITE ENDS OF SAID LEVER TUMBLERS THEREBY TO SWING SAID LEVER TUMBLERS ABOUT SAID TORSIONPROOF SHAFT SO THAT THE PRESS BEAM IS RAISED AND LOWERED FROM AND ONTO A PRESS TABLE IN PERMANENT PARALLEL RELATIONSHIP TO THE LATTER.

' I I HYDRAULICALLY OPERATED POWER PRESS Filed Feb. 13, 1969 IIVVENTOR' R7BRT HEITMANN United States Patent Oihce 3,552,183 HYDRAULICALLY OPERATED POWER PRESS Robert Heitmann, 21-23 Brauhausstrasse, Hamburg, Germany Filed Feb. 13, 1969, Ser. No. 799,011 Int. Cl. B21j 9/18 US. Cl. 72450 2 Claims ABSTRACT OF THE DISCLOSURE A hydraulically operated power press comprises two horizontally spaced upright members which are interconnected by means of a torsionproof shaft mounted between them, and an upper torsionproof cross member which extends parallel to said shaft. Two lever tumblers are mounted on said shaft and extend in close parallel rela tionship to the inner sides of said upright members. A press beam is associated with said two lever tumblers through the intermediary of two pressure bars pivoted to one end of each of said lever tumblers. Two hydraulic rams are provided to act upon the opposite ends of said lever tumblers thereby to swing said lever tumblers about said torsionproof shaft so that the press beam is raised and lowered from and onto a press table in permanent parallel relationship to the latter.

BACKGROUND OF THE INVENTION This invention relates to a hydraulically operated press for edging, shearing and like work.

Fully hydraulic presses of this type have already become known in the art. However, their operation is critical for unbalanced press work and if the press is subjected to single-end loads.

To balance loads applied to one end of the press beam provision has already been made of compensation rods and regulating valves. In most cases these means become effective only after a certain inclined position has been reached. In other conventional forms, multistage hydraulic pumps were provided for each hydraulic ram to admit exact pressure rates to each hydraulic cylinder. These means are very expensive and susceptible to failure.

It is also known directly to connect the piston rods of double-cylinder edging presses to the press beam. In this case, the press beam cannot be prevented from assuming an inclined position. However, a very extensive stroke may be chosen.

SUMMARY OF THE INVENTION It is the object of the present invention to provide a hydraulically operated power press for edging, shearing and like work, which is of simple construction and in which permanent parallel relationship between the press beam and the press table is mechanically ensured by means of two hydraulic rams.

To attain this object, the present invention provides a hydraulically operated power press which comprises tWO horizontally spaced upright members; a torsionproof' shaft extending between and through said upright members; an upper torsionproof cross member extending parallel to said shaft; two lever tumblers mounted on said shaft and extending in close parallel relationship to said upright members; a press beam associated with said two lever tumblers through the intermediary of two pressure bars pivoted each to one end of said lever tumbler; and two hydraulic rams acting upon the other end of each of said lever tumblers to pivot said lever tumblers about said torsionproof shaft thereby to raise and lower the press beam from and onto a press table in permanent parallel relationship to the latter.

Patented Jan. 5, 1971 The arrangement of the lever tumblers is most favorable since the upper cross member which interconnects the lever tumblers and may be made of inexpensive and unfinished structural steel avoids or substantially avoids torsion of the shaft when the power press is subjected to unbalanced load, so that the arrangement of two hydraulic rams mechanically provides permanent parallel relationship between the press beam and the press table.

Omitting the interconnecting upper cross member would result in the necessity of inadmissibly increasing the diameter of the shaft to provide satisfactory torsionproof in the case when a great pressing power is applied. Such increase in diameter, however, cannot be encountered. The upper cross member being torsionproof and of heavy weight without causing great expenses advantageously provides a counterweight for the press beam. Thus, use can be made of single-acting hydraulic rams, in which hydraulic pressure is applied to only one end face of the plunger, the return stroke being caused by the counterweight.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the invention will now be described by way of example and with reference to the accompanying drawing in which:

FIG. 1 is a top plan view of a hydraulically operated power press according to the invention, and

FIG. 2 is an end view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing shows a hydraulically operated power press according to the invention which comprises two horizontally spaced upright members 1 and 2 and a torsionproof shaft 3 extending between and through said upright members so that its ends 4 project therefrom for the connection thereto of control means, not shown. Two lever tumblers 5 are secured to the shaft 3 adjacent the inner sides of the upright members 1 and 2 and have one of their ends connected to an upper torsionproof cross member 6. Each of the free ends 7 of the upper cross member 6 is acted upon by a hydraulic ram 8 which may be pivotally secured to the outer side of its neighbor-upright member. Alternatively, the hydraulic rams 8 may be pivoted to the end faces of a lower cross member 13 rigidly interconnecting the two upright members 1 and 2. In still another form of construction the hydraulic rams 8 may comprise stationary cylinders in which a movable plunger reciprocates.

The other ends 9 of the lever tumblers 5 are connected through the intermediary of two pressure bars 10 to a press beam 11 which cooperates with a matrix 12 as shown in FIG. 2.

Advantageously, each lever tumbler 5 and the hydraulic ram 8 associated therewith are located on opposite sides of the upright members 1 and 2, respectively.

As the two bearings for the shaft 3 in the lever tumblers 5 may be spaced from the pivotal points of both the pressure bars 10 of the press beam 11 and the two hydraulic rams 8 to any desired extent, a stroke equivalent to that of fully hydraulic power presses may be readily obtained. Furthermore, the possibility of choosing a greater lever length between the bearings of the shaft 3 and the pivotal points of the rams 8 results in a reduction of the ram power in relation to the actual press power.

Thus, the diameter of the pistons of the hydraulic rams can be kept much smaller than in the case of directly acting short hydraulic rams, which smaller diameter of course necessitates a correspondingly longer length of stroke. However, the smaller rams are less expensive and the longer length of the stroke involves relatively low additional cost only.

As the distance between the shaft bearings in the lever tumblers 5 and the press beam 11 is of considerable length, the throat in each of the upright members beneath said shaft bearings will be subjected to no or to only unimportant load so that the section of the upright members above the throats will not deflect or will deflect much less than in conventional fully hydraulic presses.

What is claimed is:

1. A hydraulically operated power press comprising (a) two horizontally spaced upright members;

(b) a torsionproof shaft extending between and through said upright members;

(c) an upper torsionproof cross member extending parallel to said shaft;

(d) two lever tumblers mounted on said shaft and extending in close parallel relationship to said upright members;

(e) a press beam associated with said two lever tumblers through the intermediary of two pressure bars References Cited UNITED STATES PATENTS 6,520 6/1875 Payne 72-450 2,558,071 6/1951 Castle l0027l 3,051,078 8/1962 Webster l00271 3,187,533 6/1965 Cave 100271 3,222,913 12/1965 Leopold '72-450 3,472,057 10/1969 Persico 72450 CHARLES W. LANl-lAM, Primary Examiner G. P. CROSBY, Assistant Examiner US Cl. X.R. 

